Carton locking device



28, 1956 A. c. FRITZ 2,760,710

CARTON LOCKING DEVICE Filed Oct. 22, 1953 2 Sheets-Sheet 1 L a: as

INVENTOR. AR LYN G FRITZ ATT'OR N EYS Aug. 28, 1956 A. c. FRITZ 2,760,710

CARTON LOCKING DEVICE Filed OCZ. 22, 1953. 2 Sheets-Sheet 2 INVENTOR.

ARLYN c. FRITZ [/E 3 f: z

ATTORNEYS CARTON LOCKING DEVICE Arlyn Conrad Fritz, Menasha, Wis., assignor t Marathon Corporation, Rothschild, Wis., a corporation of Wiscousin Application October 22, 1953, Serial No. 387,709

2 Claims. (Cl. 22945) This invention relates to an improved form of locking means for cartons or boxes and the like commonly made from paperboard or similar material. As is well known, paperboard cartons or boxes are used in quantities of many billions each year, and in a large proportion of such uses it is desirable that an adhesive not be used, or at least not used in certain portions of the construction where none the less a secure closure is required. To obtain such a closure, a number of various locking means have been devised, to suit particular purposes and for use with particular qualities of carton material.

1 nited States Patent 0 F Due of the general types of locking means thus devised is commonly known in the carton industry as an arrow lock, the name arising from the fact that the male member of the locking means commonly has a substantially arrow-like shape and appearance.

My invention relates to a lock of the type which might be considered an arrow lock, although it provides a certain utility previously unknown in this field. It is frequently very desirable that an arrow or other lock in a particular usage provide a firm attachment or closure, with neither side nor end play of the portions locked together. However, it has been inherent in arrow-type locks that a large degree of side play is permitted. This is because the leading portion of the arrow-like member has a lateral dimension greater than that of the portion immediately following, and since it is the leading portion which must pass through the complementary locking slit on the other member, side play results when the fully locked position is reached with the narrower portion lying within the slit.

My inveniton includes a considerable modification of the arrow-type lock, resulting in elimination of this side play, and providing a locking means which give a firm and secure attachment or closure.

The construction by which I provide this improvement will be readily apparent from the following description and accompanying drawings, in which:

Figure l is a plan view of a paperboard blank for making a carton embodying my invention,

Figure 2 is a perspective view of a carton set up from the blank shown in Figure l, in a preliminary stage of the locking operation,

Figure 3 is a bottom view of the carton shown in Figure 2, with the locking operation in an intermediate stage,

Figure 4 is a bottom dew similar to Figure 3 showing the carton with the lock completely engaged, and

Figure 5 is a top perspective view, showing the erected carton, and showing the completely-engaged lock as viewed from the inside of the carton.

Referring first to Figure 1, the carton may be made from a single paperboard blank 10, suitably cut and scored to provide a bottom wall or panel 11, a rear wall 12, a top wall 13, a front wall 14 and a locking flap or panel 15 opposed to panel 11, these walls and flaps in order being hingedly separated from each other along score lines 16, 17, 18 and 19, respectively. Dust flaps 20 and 21 are hinged to side walls 22 and 23 along score lines 24 and 25, the side walls in turn being hingedly connected to the side edges of top wall 13 along score lines 26 and 27, all respectively.

Dust tabs 28 are hingedly connected to the side edges of side walls 22 and 23 along score lines 29, and are separated from rear and front walls 12 and 14 by cut lines 30. Adjacent the free edge of bottom panel 11 and extending toward panel 15 (Figure 2) is a pair of parallel, longitudinally situated spaced slits or cut lines 31a and 31b, to the inner ends of which is connected a pair of transverse, laterally-spaced slits or cuts 32. Each of slits 32 terminates at its remote end in a rearwardly angled portion 33 extending away from the free end edge of panel 11 and away from panel 11 as seen in Figure 2 with the carton ready for locking. A window such as at 34 may be cut from top wall 13, and if desired this window may of course be covered by cellophane or other transparent material. The free end edge of the locking panel 15 has the male or arrow-like locking member formed thereon and divided into two parts comprising a pair of half-arrow members 35a and 3512. Members 35a and 35b are laterally spaced or separated by a cut out portion defined by transverse cut out line 36, and generally longitudinal lines 37 defining the side edges of the space. The outer ends of the locking members 35a and 35b have hook-like portions 40 formed thereon by locking slots cut therein by curved cut-out lines or edges 38. Aligned slits 32 are substantially parallel to members 35a and 35b, that is, the slits are substantially parallel to lines drawn simultaneously through similar points on each of members 35a and 35b.

The overall width A of the arrow-like locking member is substantially equal to the distance B between the remote ends of female slits 32, 33. The distance C between the inner ends of female slits 32 i substantially equal to the length D of line 36 and substantially less than the distance E between the remote ends of boundary cut .lines 37; that is, the lateral dimension of the space between male members 35a and 35b at the free end edge of the locking panel is greater than the lateral dimension of the space at the inner boundary of the space (along line 36), the first of these lateral dimensions being greater than and the second equal to the distance between slits 32.

The carton is set up as shown in Figures 2, 3, 4 and 5, with Walls 12, 14, 22 and 23 erected perpendicularly to top wall 13, tabs 28 erected parallel to and inwardly of walls 12 and 14, and panel 15, flaps 20 and 21 and bottom panel 11 parallel to top wall 13.

The engaging operation for my lock is performed as shown in Figures 2 and 3. Locking panel 15 is brought over the free end edge of bottom panel 11, whereupon a slight downward pressure on the members 35a and 35b of the male locking member will press on the areas of panel 11 bounded by slits 31a, 32 and by 3111, 33 to cause an opening of slits 32, 33, as shown in Figure 2. Referring additionally to Figure 3, members 35a and 35b may then be pushed inwardly through slits 32, 33.

It will be noted that the edges defined by slits 31a and 31b engage the edges of biased boundary lines 37, thus acting as a guide for the entrance of the male locking member. Referring particularly to Figure 3, it will be seen that the angle or curvature in slits 32, 33 cooperates with the curved leading edge of male members 35a and 35b to produce easy entrance of the male members. As the lock nears complete engagement, with the ends of boundary line 36 snug against the inner ends of slits 32, the equality of the distances C and D results in an exact centering of the male portion of the lock with the female portion, and in the completely engaged lock results in complete elimination of possible side play of the male member and locking panel 15 with respect to the female member and bottom panel 11.

As the engaging operation is continued to the position shown in Figure 4, the natural resilience of the carton material results in an attempt by the portions of bottom panel 11 lying to each side of slits 32, 33 to spring back to lie in a single plane, and this tendency results in a pressure slightly bending the remote, free hook-like portions 40 of male members 35:: and 35b inwardly of the carton beneath panel 11. Upon release of the lock-engaging pressure, the male portion will spring back very slightly, with the remote free portions 40 lying inwardly and slightly forwardly (toward the free end edge of panel 11) of slits 33 and with the edges 38 of male members 350 and 35b engaged with the edge presented by slits 32 and 33 substantially at the juncture of those slits (Figure The slight springing back of the male members 35a and 35b is insufiicient to have any material effect upon the snug engagement of edges 37 with the inner edges of cuts 31a and 31b. A snug, firm lock is thus provided, effectively free of side play of locking panel 15 with respect to bottom panel 11 and substantially free of end play of these two elements with respect to each other.

The firmness of the lock I have provided adds materially to the strength and security of the carton as a whole, and further provides the highly desirable feature of a tamperproof closure. It will be readily noted that the completely-engaged lock cannot be reopened without considerable mutilation of the carton material adjacent the lock. Consequently, and this is particularly important when foodstufis are to be packaged, the carton cannot be opened and the contents handled or tampered with without a subsequent inspection revealing the prior occurence of such activity. This is a valuable protective feature for foodstuffs and other materials openly displayed in a grocery or other store.

Although but one embodiment of my invention has been illustrated and described, obvious modifications and variations in my invention might readily be made without departing from the spirit thereof. For example, slits 31a, 31b could be eliminated or boundary lines 37 made parallel and strictly longitudinal without destroying the operativeness of the lock, though there would result a marked decrease in the facility with which the lock could be engaged. Similarly, angled cuts '33 could be eliminated, with a mere decrease in the tenacity of the locking engagement. Other modifications may readily be envisaged. It is therefore to be understood that no limitations upon my invention are intended except as are set forth in the appended claims. It is further obvious that, although the claims for definiteness describe my lock as used in a carton, the lock will work quite as Well for such articles as bands or collars and the like, such as shirt bands and similar articles, and such use isintended to and obviously should be covered by the claims.

I claim:

1. Locking means for a carton, the carton including a pair of opposed panels to be locked together, the locking means comprising a pair of laterally spaced male members formed on one of said panels, each of said male members having a hook-like portion formed on its laterally remote end, and female means in the other of said panels including a pair of laterally spaced, aligned slits, said slits being positioned parallel to a line drawn simultaneously through a similar point on each of said hooklike portions, the adjacent ends of said aligned slits each having one of a pair of cut lines connecting therewith and extending toward said one panel, the spacing between said male members being defined by a pair of cut lines and at the inner boundary thereof being substantially equal to the spacing between said slits, said slits and firstrnentioned cut lines defining portions in the other of said panels adaptable for depression upon pressure of said male members thereupon for ready opening of said aligned slits for entrance of the male members and consequent engagement of the locking means, the remote end of each of said aligned slits being angled away from said male members to cause engagement of said hook-like portions beneath the other of said panels for positive security of the lock upon engagement of said locking means.

2. Locking means according to claim 1, wherein the cut lines connecting with said aligned slits are substantially parallel to each other and perpendicular to said slits, and the cut lines defining the spacing between said male members are divergent from each other in the direction away from said one panel, the spacing between said male members at the free end edge of said one end panel being substantially greater than the spacing between said aligned slits, and the spacing between said male members at the inner boundary theerof being substantially equal to the spacing between said aligned slits.

References Cited in the file of this patent UNITED STATES PATENTS 1,923,065 Clemens Aug. 22, 1933 2,160,164 Palmer May 30, 1939 2,190,433 Palmer Feb. 13, 1940 2,304,362 Huye Dec. 8, 1942 2,677,493 Wanda May 4, 1954 FOREIGN PATENTS 106,874 Sweden Jan. 14, 1943 

